Semiconductor wafers are generally produced in relatively large dimension in the form of large diameter disks. The semiconductor wafers are subsequently diced and cut into semiconductor chips of much smaller size for use in the production of integrated circuits. The geometric shape of the peripheral area of a semiconductor chip has a profound impact on the physical integrity of the chip. Traditionally, semiconductor chips were formed by cutting a processed wafer into predetermined pieces using a straight cutting device, such as a mechanical saw or a laser-cutting device. These mechanical straight-cutting tools create semiconductor chips that have square or rectangular shapes. Because of the ninety-degree corners in the square and rectangular shapes, there is always a tremendous amount of stress occurring at the corners of these square and rectangular shaped semiconductor chips. This additional mechanical stress causes physical defects, such as chipping and/or cracking at the edges of the semiconductor chips. Such physical defects often occur during the subsequent packaging process steps when the chips undergo additional stress.
FIG. 1 depicts a prior art semiconductor wafer 100 and chip 110. In this case, the semiconductor wafer 100 is cut using traditional straightedge mechanical saw 120 that follows a perpendicular dicing pattern 101. Once the semiconductor wafer 100 is cut using the mechanical saw 120, numerous chips (or dies) 110 are formed. As a result of using the mechanical saw 120 in a straight-line fashion, the resulting dies 110 have square or rectangular shapes.
FIG. 2 illustrates the problem associated with this prior art semiconductor chips 110 having a square or rectangular shape as a result of using this traditional cutting method. Specifically, as depicted in FIG. 2, there is tremendous amount of mechanical stress built-up at the ninety-degree corners 130 of the square and rectangular semiconductor chips 110. Such stress makes the semiconductor chip 110 prone to physical defects. For instance, when additional layers are being pressed onto the semiconductor chip 110 in a subsequent packaging process, the corners 130 of the semiconductor chip 110 may experience such as delamination or chipping.
When delamination occurs, for example, the physical defect would propagate inward, towards the active area of the semiconductor chip 110. Once the physical defect caused by delamination, such as a crack, reaches the active area, the semiconductor chip 110 would no longer be able to function properly and therefore fails. Some prior art semiconductor chips 110 include physical barriers to prevent propagation of cracks, such as introduction of a crack stop, these crack stops are largely ineffective as semiconductor technology advances and different materials are being used to make the chips. These measures attempt to fix the symptom rather than solving the root cause of the problem.